1. Technical Field
The present disclosure relates to cooling in network switches.
2. Related Art
A computer network is an interconnected group of computers and other devices, such as storage devices. All networks are made up of basic hardware building blocks to interconnect network nodes. These building blocks include network interface cards (NICS), bridges, hubs, switches, and routers, for example. Each device in the network is called a node. All nodes include at least one port. An interconnect medium, such as copper wiring or optical cabling, extends between device ports.
FIG. 1 is a schematic block diagram of a typical network 30. The network 30 includes a plurality of interconnected devices, including first and second switches 32, 34, a host system 33 coupled to the second switch 34, a disk array 36 coupled to the first switch 32, and a server 38 coupled to both switches 32, 34 and to storage 40.
A switch is a multi-port device in which each port manages a simple point-to-point connection between itself and its attached system. Each switch port can be attached to a host system, a server, a peripheral, an I/O subsystem, a bridge, a hub, a router, or even another switch. A switch receives data packets from one port and automatically routes them to other ports based on addresses contained in the packets.
Switches include a plurality of modules supported by a chassis. The modules are printed circuit boards (PCBs), and include one or more integrated circuit (IC) devices, or chips, on at least one surface. In operation the chips generate heat that must be dissipated in order to keep the switch operating efficiently. One problem that plagues switch cooling is “stack rise.” Stack rise occurs when cooling air passes over multiple chips in succession. Each chip heats the passing cooling air so that downstream chips always receive warmer, or preheated, cooling air. These downstream chips are more susceptible to overheating, which decreases switch performance.